Dawson, a former centre for the Canterbury Rams in the National Basketball League, has been banned by the Sports Tribunal of New Zealand after he tested positive for banned Beta-2 Agonist higenamine after an in-competition test on May 27.

It followed a previous 12-month suspension issued in 2014 after the 28-year-old, then playing for the Southland Sharks, tested positive for hormone therapy for using tamoxifen.

Tamoxifen is a breast cancer drug listed on the World Anti-Doping Agency prohibited list as a banned hormone and metabolic modulator.

Dawson, who joined Canterbury in 2015 after completing his first suspension, claimed at the time to have made a careless mistake by not checking prescriptions.

He was provisionally suspended for a second time on September 4 before the case was confirmed.

The fact that it was a second violation explained why a four-year ban was issued.

The Tribunal noted that they had "significant difficulties contacting Mr Dawson who lives in Western Australia" thereafter.

He formally admitted the violation on October 18, but requested a hearing to appeal for an "appropriate sanction".

This was set for November, only for Dawon not to appeal.

"He failed to do so, and the Tribunal adjourned the hearing to allow Mr Dawson an opportunity to participate in a rescheduled hearing," the full verdict said.

"The Tribunal cautioned Mr Dawson from the outset that he was subject to substantial mandatory penalties, offering assistance and advice.

"Despite numerous efforts to engage Mr Dawson throughout the process, and to accommodate his overseas residence and work commitments, Mr Dawson did not take any action to mitigate the consequences and declined to attend the rescheduled hearing.

"He said he had outlined his circumstances and was satisfied for the matter to be dealt with in his absence.

"A further hearing date was set, and the matter determined but without Mr Dawson's direct participation."

Dawson has been handed a suspension backdated to July 31, 2017.

He will thus be ineligible until July 30, 2021.

The International Basketball Federation claim the sport is "low-risk" for doping due to the "low" number of cases that have arisen.